1. Technical Field
The present invention relates to a registration technology of surface models, more specifically to a technology for registration of a plurality of partial surface models obtained through an intra-oral scanner.
2. Background Art
Three-dimensional models need to be made as precisely as possible for orthodontic procedures or implant procedures in dentistry. The 3D surface model of a dental object is often generated by making a plastic model or by obtaining a radiograph. However, making a model takes a long time and requires a skilled technique of a dentist when the dental object is made. Accordingly, the radiograph is used instead of making the 3D surface model, but not only is the radiograph equipment expensive, but a high quality of photograph requires a large amount of radiation.
Introduced for assessing the 3D geometric structure of teeth is an intra-oral laser scanner, which is now recognized as an alternative to the radiograph. However, since the laser scanner has a small field of view (FOV), a single scanned surface model is not sufficient to encompass the entire teeth or dental object. Therefore, the single scanned surface model needs to be combined with another surface model that is obtained from another perspective, to generate the dental model. In this process of combining, it is imperative to find an area where the adjacent surface models overlap with each other and perform registration for this area.
In two common ways of registration, corresponding points are configured within the overlapped area of the two surface models, and then a transformation method is sought between the corresponding points, or a transformation method is sought to minimize the difference in distance between the two surface models. However, the transformation method is hardly found in both ways because it is not easy to find the overlapped area and a particular point of one surface model often corresponds with plural points of the other surface model.